Deformable beam transport system with extraction port

ABSTRACT

A beam transport device for a particle beam traversing first and second sections of a beam tube includes a pair of bellows each having an end mounted to an associated one of the sections of the beam tube. Interposed of the bellows and sealed to associated ends thereof are a particle-beam-extraction window and a rigid hollow member juxtaposed of the extraction window. Motive means are coupled to provide motion to the extraction window and rigid hollow member whereby they may be respectively aligned with the particle beam upon deformation of the bellows.

United States Patent Nixon et al.

[ 1 1 3,723,785 1 Mar. 27, 1973 [54] DEFORMABLE BEAM TRANSPORT SYSTEMWITH EXTRACTION PORT Inventors: Jack M. Nixon, Wheaton; Warren J.

Ramler, Elmhurst, both of Ill.

The United States of America as represented by the United States AtomicEnergy Commission Filed: May 23, 1972 Appl. No.: 256,051

Assignee:

US. Cl. ..313/63, 250/495 B, 313/62,

313/148 Int. Cl. ..H 05h 9/00 Field of Search ..3l3/62, 63, 148; 250/495B Primary Examiner-Roy Lake Assistant Examiner-Darwin R. HostetterAttorney-Roland A. Anderson [57] ABSTRACT 6 Claims, 4 Drawing Figuresall? I ll EXPE/P/ MEN 7 PAIENTEBMARZ'! I973 SHEET 1 [IF 2 NEW? MMQEEQDEFORMABLE BEAM TRANSPORT SYSTEM WITH EXTRACTION PORT CONTRACTUAL ORIGINOF THE INVENTION The invention described herein was made in the courseof, or under, a contract with the United States Atomic EnergyCommission.

BACKGROUND OF THE INVENTION The present invention relates to particleaccelerators and more particularly to a beam transport device for suchaccelerators. Particles in todays accelerators are generally acceleratedeither in a circular orbit (as in a cyclotron or synchrotron) or in astraight line (as in a linear accelerator). The particles are 14 in beamtubes, which tubes are partially evacuated to a high vacuum, generallyof the order of 2 X Torr. After they have been accelerated, theparticles are extracted from the accelerator to effect collisions withtargets of interest. As the particles leave the accelerator and progresstowards the target, the particle beam deteriorates in quality. That is,the further the distance to the target the poorer the quality of thebeam. The quality of the beam degrades in two respects. First, the spacecharge causes the beam to debunch whereby the beam spreads axially andspreads the pulse apart. Second, the beam also spreads radially. Theradial spreading of the beam may be compensated for by insertingrefocusing magnets along the beam tube. However, axial spreading of thebeam may not be compensated for. Thus, where it is important for theexperiment to have minimal axial spreading of the beam pulse, it isdesirable to effect the experiment as close to the accelerator aspossible. Conversely, where axial spreading of the beam pulse is notparticularly important, the experiments may be conducted away from theaccelerator using refocusing magnets to maintain minimal radialspreading of the beam pulse. Heretofore, to achieve these twoconditions, it has been necessary to disassemble the beam tubes andbreak the accelerator primary vacuum in order that one may change from arelatively close target to a target far away or, vice versa, to changefrom a target relatively far away from the accelerator to a targetimmediately adjacent the accelerator.

It is therefore one object of the present invention to provide a beamtransport for a particle accelerator, which beam transport permits theextraction of a particle beam from the accelerator either immediatelyadjacent the accelerator or removed therefrom.

It is another object of the present invention to provide an improvedbeam transport device for use in a particle accelerator.

It is another object of the present invention to provide a beamtransport device enabling extraction of the beam either immediatelyadjacent the accelerator or removed therefrom without interruption ofthe primary vacuum system of the accelerator.

Other objects of the present invention will become more apparent as thedetailed description proceeds.

In general, the beam transport device for a particle beam traversingpartially evacuated axially aligned spa tially disposed first and secondsections of a beam tubecomprises particle-beam-extraction-window meansand a first hollow member internally sized to accept said particle beamand juxtaposed said beam-extractionwindow means. A deformable secondhollow member is provided internally sized to accept said particle beamtherethrough and at one end to accept said beam-extraction-window meansand the first hollow member in juxtaposed relationship. Means mount thesaid one end of the deformable second hollow member in sealed engagementto the beam-extraction-window means and one end of the first hollowmember and also mount the other end of said deformable second member insealed engagement to the first section of the beam tube to pass saidparticle beam therethrough. A deformable third hollow member is providedinternally sized to accept the particle beam and means mount one end ofthe deformable third hollow member in sealed engagement to the other endof the first hollow member and also mount the other end of thedeformable third hollow member in sealed engagement to the secondsection of the beam tube to pass the particle beam therethrough. Motivemeans provide motion to the first hollow member and thebeam-extraction-window means to permit alignment therebetween with theparticle beam.

BRIEF DESCRIPTION OF THE DRAWINGS Further understanding of the presentinvention may best be obtained from consideration of the accompanyingdrawings wherein:

FIG. 1 is a sectional view of an apparatus for the practice of thepresent invention.

FIG. 2 is a section through the apparatus of FIG. 1 along the lines 2-2;

FIG. 3 is an enlarged section of FIG. 2 along lines 3 FIG. 4 is a viewof the apparatus of FIG. 1 showing the apparatus in a differentpositional location than in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1-4 show an apparatus forthe practice of the present invention as applied to a particleaccelerator beam 10 emerging from an accelerator via a beam tube I 12.For the practice of the present invention, the beam tube 12 is dividedinto two portions, the first beam tube portion 14 and a second beam tubeportion 16. The beam transport device 17 of the present invention isinserted between these two portions 14 and 16 of beam tube 12.

The beam transport apparatus 17 comprises a pair of bellows 18 and 20whose ends are terminated in flanges 22, 24, 26 and 28, respectively. Aplate 30 having an aperture 32 therethrough sized to accept the endportion 14 of beam tube 12 is mounted on the end portion 15 of beam tube12 and welded thereto to provide a seal therewith. Further, the plate 30issized to engage the flange 24 of bellows l8 and a weld is effectedtherebetween to provide a seal between the bellows flange 24 and plate30. Similarly, a plate 34 having an aperture 36 therethrough sized toaccept the end portion 16 of beam tube 12 is mounted on the end portion16 of beam tube 12 and a weld is effected therebetween to seal the plate34 about the end portion 16 of beam tube 12. The plate 34 is sized toengage the flange 28 of bellows 20 and a weld is effected therebetweento provide a seal between the plate 34 and flange 28 of bellows 20.

A plate 38, having two apertures 40 and 42 therein sized to accept aparticle-beam-extraction window 44 and a hollow beam tube 46 injuxtaposed relationship with respect to each other, is mounted so thatit engages the flange 22 of bellows 18. A butt weld is effected betweenthe flange 22 of bellows l8 and the plate 38 to effect a sealtherebetween. The beam tube 46 is internally sized to accept theparticle beam and is disposed within the aperture 42 of plate 38. A weldis effected between the plate 38 and the beam tube 46 to form a sealtherebetween. The window 44, as shown in FIG. 3, comprises a windowframe 48 housing a foil 50 which is transparent to the beam 10 butmaintains the partial vacuum of the accelerator. The window frame ismounted to the plate 38 so as to effect with an O-ring seal 49 ascalable engagement therewith about aperture 40. A plate 52 having anaperture therethrough positioned and sized to accept the beam tube 46extending from plate 38 is sized to engage the flange 26 of bellows 20.A butt weld is made between the flange 26 of bellows and the plate 52 toeffect a seal therebetween. Similarly, a weld is made about the beamtube 46 and the plate 52 to effect a seal therebetween.

A rigid U-frame member 56 is mounted to the plates 52 and 38 and amotive device, such as an air cylinder 58, is mechanically coupled tothe U frame 56 to provide reciprocating motion normal to the axis of thebeam 10. Thus, movement of the piston of the air cylinder 58 impartsreciprocating motion to the beam tube '46 and the window 44 to permitthe positioning of the window 44 or the beam tube 46 in line with theaxis of the beam 10.

In operation, the air cylinder 58 is actuated to provide linear motionto the beam tube 46 and window 44 normal to the axis of the beam 10.Depending upon whether extraction of the beam is desired immediatelyadjacent the accelerator or downstream from the accelerator, the aircylinder 58 is actuated to move the window 44 or the beam tube 46 inline with the axis of the beam 10.

FIG. 1 illustrates the air cylinder 58 actuated to align the window 44with the beam 10 to permit extraction of the beam 10 immediatelyadjacent the accelerator.

FIG. 4 illustrates the air cylinder 58 actuated to align the beam tube46 with the beam 10 to permit the beam 10 to progress downstream fromthe accelerator.

It will be appreciated that these two conditions, namely extraction ofthe beam immediately adjacent the accelerator or transmission of the.beam downstream from the accelerator, are accomplished using thestructure of the present invention without disconnecting any beam tubesor affecting the primary partial vacuum of the accelerator. It will befurther appreciated that using the structure of the present inventionthe duty factor of experiments on an accelerator is markedly increased,since no lost time is effected in changing beam tubes or losing thevacuum.

The structure of the present invention has been successfully constructedand utilized on a linear accelerator. It is not restricted to linearaccelerators and may be used on other types of accelerators. With thelinear accelerator using a 3-inch diameter beam tube 12, the bellows l8and 20 were each made of stainless steel and had an internal diameterof6 inches and an unextended length of 6 inches. The beam tube 46 was ofstainless window means steel and had a length of 14 inches and aninternal diameter of 3 inches to accommodate the beam 10. The window 44had an effective window diameter of approximately two inches andutilized l-mil double aluminum foils transparent to the beam 10. Theplates 30, 34, 38 and 52 were also of stainless steel. Theaforedescribed sizes permitted a lateral radial motion of approximately3 k inches, permitting the alignment of the accelerator beam 10 eitherthrough the window 44 or the hollow beam tube 46. It will be appreciatedthat the relative lengths of the bellows l8 and 20 and the beam tube 46may be changed to permit greater lateral radial movement or greater areafor experimental equipment between the bellows l8 and 20.

Persons skilled in the art will, of course, readily adapt the teachingsof the present invention to structure far different than thoseillustrated in the drawings and described above. Accordingly, the scopeof protection afforded the present invention should be determined onlyin accordance with the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A beam transport vdevice for a particle beam traversing partiallyevacuated axially aligned spatially disposed first and second sectionsof a beam tube comprising particle-beam-extraction-window means, a firsthollow member juxtaposed of said beam-extractionwindow means andinternally sized to accept said particle beam, a deformable secondhollow member internally sized to accept said particle beam therethroughand at one end to accept said beam-extraction-window means and firsthollow member in juxtaposed relationship, means for mounting the saidone end of said deformable second hollow member in sealed engagement tosaid beam-extraetion-window means and one end of said first hollowmember, means for mounting the other end of said deformable secondmember in sealed engagement to said first section of said beam tube topass said particle beam therethrough, a deformable third hollow memberinternally sized to accept said particle beam, means for mounting oneend of said deformable third hollow member in sealed engagement to theother end of said first hollow member, means for mounting the other endof said deformable third hollow member in sealed engagement to saidsecond section of said beam tube to pass said particle beamtherethrough, and means for providing motion to said first hollow memberand said beamextractionto permit respective alignment therebetween withsaid particle beam.

2. The apparatus according to claim 1 wherein said deformable secondmember and said first hollow member and beam-extraction-windowmountingmeans comprises a bellows internally sized to accept said first hollowmember and said beam-extraction-window means in juxtaposed coextensiverelationship from one end thereof, and a plate sealably disposed abouteach,

of said first hollow member and beam-extraction-window means andsealably mounted to said one end of said bellows. v

3. The apparatus according to claim' 1 wherein said deformable thirdhollow member comprises a bellows internally sized to accept saidparticle beam therethrough.

4. The apparatus according to claim 1 wherein said motion means comprisemotive means reciprocativally operable substantially normal to the axisof said particle beam and coupling means connecting said motive means toimpart reciprocal motion to said first hollow member and saidbeam-extraction-window means to permit the respective alignment thereofwith said particle beam.

5. The apparatus according to claim 1 wherein said deformable second andthird hollow members and said sealing means therefor comprise a firstbellows internally sized to accept said first hollow member and saidbeam-extractiomwindow means, a first plate sealably mounted about saidfirst portion of said beam tube and to one end of said first bellows, asecond plate sealably mounted about one end of said first hollow memberand said beam-extraction-window means and to the other end of said firstbellows, said first hollow member and said beam-extraction-window meansbeing juxtaposed and coextensive from said second plate, a secondbellows internally sized to accept said particle beam, a third platesealably mounted about said first hollow member and to one end of saidsecond bellows, and a fourth plate sealably mounted about said secondsection of said beam tube and to the other end of said second bellows.

6. The apparatus according to claim 5 wherein said first hollow memberand beam-extraction-window moving means comprise motive means disposedto provide reciprocative motion essentially normal to the axis of saidparticle beam, and means connected between said motive means and saidsecond and third plates to translate said reciprocative motion to saidfirst hollow member and said beam-extraction-window means and effectrespective alignment thereof with said particle beam.

1. A beam transport device for a particle beam traversing partially evacuated axiaLly aligned spatially disposed first and second sections of a beam tube comprising particle-beamextraction-window means, a first hollow member juxtaposed of said beam-extraction-window means and internally sized to accept said particle beam, a deformable second hollow member internally sized to accept said particle beam therethrough and at one end to accept said beam-extraction-window means and first hollow member in juxtaposed relationship, means for mounting the said one end of said deformable second hollow member in sealed engagement to said beam-extraction-window means and one end of said first hollow member, means for mounting the other end of said deformable second member in sealed engagement to said first section of said beam tube to pass said particle beam therethrough, a deformable third hollow member internally sized to accept said particle beam, means for mounting one end of said deformable third hollow member in sealed engagement to the other end of said first hollow member, means for mounting the other end of said deformable third hollow member in sealed engagement to said second section of said beam tube to pass said particle beam therethrough, and means for providing motion to said first hollow member and said beam-extraction-window means to permit respective alignment therebetween with said particle beam.
 2. The apparatus according to claim 1 wherein said deformable second member and said first hollow member and beam-extraction-window mounting means comprises a bellows internally sized to accept said first hollow member and said beam-extraction-window means in juxtaposed coextensive relationship from one end thereof, and a plate sealably disposed about each of said first hollow member and beam-extraction-window means and sealably mounted to said one end of said bellows.
 3. The apparatus according to claim 1 wherein said deformable third hollow member comprises a bellows internally sized to accept said particle beam therethrough.
 4. The apparatus according to claim 1 wherein said motion means comprise motive means reciprocativally operable substantially normal to the axis of said particle beam and coupling means connecting said motive means to impart reciprocal motion to said first hollow member and said beam-extraction-window means to permit the respective alignment thereof with said particle beam.
 5. The apparatus according to claim 1 wherein said deformable second and third hollow members and said sealing means therefor comprise a first bellows internally sized to accept said first hollow member and said beam-extraction-window means, a first plate sealably mounted about said first portion of said beam tube and to one end of said first bellows, a second plate sealably mounted about one end of said first hollow member and said beam-extraction-window means and to the other end of said first bellows, said first hollow member and said beam-extraction-window means being juxtaposed and coextensive from said second plate, a second bellows internally sized to accept said particle beam, a third plate sealably mounted about said first hollow member and to one end of said second bellows, and a fourth plate sealably mounted about said second section of said beam tube and to the other end of said second bellows.
 6. The apparatus according to claim 5 wherein said first hollow member and beam-extraction-window moving means comprise motive means disposed to provide reciprocative motion essentially normal to the axis of said particle beam, and means connected between said motive means and said second and third plates to translate said reciprocative motion to said first hollow member and said beam-extraction-window means and effect respective alignment thereof with said particle beam. 